[media] stk1160: Stop device and unqueue buffers when start_streaming() fails

If start_streaming() fails (e.g. out of memory) the driver needs to
rewind the start procedure. This implies possibly stopping the device
and clearing the buffer queue.

Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>